Enhanced luminescent response of a fibre-optic sensor for H 2O 2 by a high-salt-concentration medium

Abstract

A sensitive H 2O 2 biosensor based on the luminol-peroxidase system has been developed. Enhancement of the light emission is obtained with a novel approach consisting of the use of a high-salt-concentration reaction medium. This enhancement phenomenon is just as effective on soluble peroxidase as on immobilized peroxidase. The magnitude of enhancement depends on the hydrogen peroxide concentration. With the biosensor associated with the FIA system, it varies from one to eight in the presence of 3 M KCl and from three to eight in the presence of 3 M NaCl for the range 6.25 pmol-25 nmol of injected H 2O 2. With KCl or NaCl, at a concentration of 3 M, the coefficient of variation is 3.7 or 2.9%, respectively, for 40 replicates of 250 pmol H 2O 2. After 80 assays performed within two days, no decrease of the biosensor response is perceptible. After four days of intensive use, the biosensor response represents 83% of the initial value.